Fluid dynamic bearing motor including molded plastic

ABSTRACT

A fluid dynamic bearing motor and method are described, wherein motor components, including complex shaped motor components, are molded of plastic. The molding ensures form control and dimensional control thereby accomplishing design requirements, and eliminating or reducing component costs and component machining. The mold can be shaped to form various motor geometries, thereby eliminating the need for multiple component assembly and related assembly costs. In an aspect, a plastic integral motor hub is formed by injection molding. Alternatively, a plastic motor hub is affixed to a metal sleeve. In another aspect, fluid containment structures are molded into the motor component, reducing the number of components as compared with machined metal components. In a further aspect, bearing structures such as grooves are molded into the motor component, thereby eliminating processes such as electrochemical machining. In yet a further aspect, a plastic hub faces a thrustplate, reducing expensive sleeve machining.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.11/975,046, filed Oct. 17, 2007, now U.S. Pat. No. 8,033,731.

BACKGROUND

Disc drive memory systems store digital information that is recorded onconcentric tracks of a magnetic disc medium. At least one disc isrotatably mounted on a spindle, and the information, which can be storedin the form of magnetic transitions within the discs, is accessed usingread/write heads or transducers. A drive controller is conventionallyused for controlling the disc drive system based on commands receivedfrom a host system. The drive controller controls the disc drive tostore and retrieve information from the magnetic discs. The read/writeheads are located on a pivoting arm that moves radially over the surfaceof the disc. The discs are rotated at high speeds during operation usingan electric motor located inside a hub or below the discs. Magnets onthe hub interact with a stator to cause rotation of the hub relative tothe stator. One type of motor has a spindle mounted by means of abearing system to a motor shaft disposed in the center of the hub. Thebearings permit rotational movement between the shaft and the sleeve,while maintaining alignment of the spindle to the shaft. The read/writeheads must be accurately aligned with the storage tracks on the disc toensure the proper reading and writing of information.

These disc drive memory systems are being utilized in progressively moreenvironments besides traditional stationary computing environments.Recently, disc drive memory systems are incorporated into devices thatare operated in mobile environments including digital cameras, digitalvideo cameras, GPS devices, video game consoles and personal musicplayers, in addition to portable computers. As such, performance anddesign needs have intensified including improved resistance to shock,improved robustness and reduced power consumption. Further, a demandexists for increased storage capacity and smaller disc drives, which hasled to the design of higher recording areal density such that theread/write heads are placed increasingly closer to the disc surface.Because rotational accuracy is critical, disc drives currently utilize aspindle motor having fluid dynamic bearings (FDB) between a shaft andsleeve to support a hub and the disc for rotation. In a hydrodynamicbearing, a lubricating fluid provides a bearing surface between a fixedmember and a rotating member of the disc drive. Hydrodynamic bearings,however, suffer from sensitivity to external loads or mechanical shock,which can jar fluid from the bearing. Fluid containment is critical tothe life of a motor, and designs have tended to increase componentcomplexity.

Presently, motor component design complexity requires many machiningoperations, which increases the costs of components. The basic componentgeometry of a motor component may require removal of a substantialamount of metal, depending on the form factor, and therefore themachining costs are significant in relation to the overall finishedmotor cost. Multiple components must be precisely assembled in order toachieve a motor construction that is able to perform with or as a fluidbearing, and that allows appropriate fluid containment. Electrochemicalmachining (ECM) processes typically incorporate bearing structures(i.e., grooves and lands) into metal parts. However, to utilize ECM,metal parts and accurate process interface surfaces are required. Metalparts may also require additional coating (i.e., DLC) to ensureappropriate wear performance.

SUMMARY

The present invention provides a molded plastic component for fluiddynamic bearing (FDB) motors. The FDB motor includes a fluid dynamicbearing containing fluid defined between an inner component and an outercomponent, wherein the inner component and the outer component arepositioned for relative rotation. At least a portion of the outercomponent is plastic formed by a molding process. The outer componenthas a plastic surface that faces and defines a fluid bearing with theinner component. Alternatively, the outer component is affixed to ametal component, wherein the metal component has a metal surface thatfaces and defines a fluid bearing with the inner component. These andvarious other features and advantages will be apparent from a reading ofthe following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and many of the attendant advantages of thisinvention will become more readily appreciated by reference to thefollowing detailed description, when taken in conjunction with theaccompanying drawings, wherein:

FIG. 1 is a top plan view of a disc drive data storage system in whichthe present invention is useful, in accordance with an embodiment of thepresent invention;

FIG. 2A is a sectional side view of a fluid dynamic bearing motor thatcan be used in a disc drive data storage system as in FIG. 1, wherein atleast a portion of an outer component is plastic formed by a moldingprocess, and wherein the outer component has a plastic surface thatfaces and defines a bearing with the inner component, in accordance withan embodiment of the present invention;

FIG. 2B is another sectional side view of a fluid dynamic bearing motorthat can be used in a disc drive data storage system as in FIG. 1,wherein at least a portion of an outer component is formed of plastic bya molding process, and a backiron extends axially adjacent to a magnetand also radially adjacent to a bottom portion of the magnet, inaccordance with an embodiment of the present invention;

FIG. 3 is a sectional side view of the fluid dynamic bearing motor as inFIG. 2A, wherein draft is illustrated on the integral molded plasticouter component, in accordance with an embodiment of the presentinvention;

FIG. 4 is a perspective image of the fluid dynamic bearing motor as inFIG. 2A, wherein the plastic outer component defines a primary bearingand a secondary bearing with an inner component, and wherein a draftfree rib is shown on an outer diameter of the outer component, inaccordance with an embodiment of the present invention;

FIG. 5A is a sectional side view of a fluid dynamic bearing motor havinga sleeve extending about a counterplate and a thrustplate;

FIG. 5B is a sectional side view of a fluid dynamic bearing motorwherein the plastic outer component is a hub that has a thrustplatefacing surface, in accordance with an embodiment of the presentinvention;

FIG. 6A is a sectional side view of a fluid dynamic bearing motorwherein the plastic outer component is a hub that has a thrustplatefacing surface, wherein the thrustplate facing surface includes grooves,in accordance with an embodiment of the present invention;

FIG. 6B is a plan view of the hub in FIG. 6A showing the grooves on thethrustplate facing surface, in accordance with an embodiment of thepresent invention;

FIG. 6C is a perspective image of the hub in FIG. 6A, in accordance withan embodiment of the present invention;

FIG. 7 is a sectional side view of a fluid dynamic bearing motor whereina plastic outer component is affixed to a metal component wherein themetal component faces and defines a bearing with a conical innercomponent, and wherein the plastic outer component includes a fluidcontainment structure formed by the molding process, in accordance withan embodiment of the present invention;

FIG. 8 is a sectional side view of a fluid dynamic bearing motor whereina plastic outer component is affixed to a metal component wherein themetal component faces and defines a bearing with a conical innercomponent, and wherein the inner component attaches to a top cover, inaccordance with an embodiment of the present invention;

FIG. 9 is a sectional side view of a fluid dynamic bearing motor whereina plastic outer component is affixed to a metal component wherein themetal component faces and defines a bearing with a dual conical innercomponent, and wherein the inner component attaches to a top cover, inaccordance with an embodiment of the present invention; and

FIG. 10 is a sectional side view of a fluid dynamic bearing motorwherein a plastic outer component faces and defines a bearing with aninner component, wherein a plastic cone support is affixed to the innercomponent, and a plastic cone is affixed to the plastic cone support,wherein the plastic cone support and the plastic cone define a fluidpassageway therebetween, in accordance with an embodiment of the presentinvention.

DETAILED DESCRIPTION

Exemplary embodiments are described with reference to specificconfigurations. Those of ordinary skill in the art will appreciate thatvarious changes and modifications can be made while remaining within thescope of the appended claims. Additionally, well-known elements,devices, components, methods, process steps and the like may not be setforth in detail in order to avoid obscuring the invention.

As described herein, the present invention provides a molded plasticcomponent for fluid dynamic bearing (FDB) motors, including conical,spherical or hemispherical motor designs. Motor components, includingcomplex shaped motor components, are molded of plastic. The moldingensures form control and dimensional control thereby accomplishingdesign requirements, and eliminating additional component costs, andeliminating or reducing component machining. In an embodiment, injectionmolding is employed to form a motor component, and the mold design isshaped to form various motor geometries, thereby eliminating the needfor multiple component assembly and related assembly costs. In anembodiment, a plastic integral motor hub that faces and defines abearing with a shaft is formed by injection molding. Alternatively, aplastic motor hub is affixed to a metal sleeve, wherein the metal sleevedefines a bearing with the shaft. In an embodiment, fluid containmentstructures and features are directly molded into the plastic motorcomponent, thereby reducing the number of components as compared withmachined metal components. Additionally, in an embodiment, bearingstructures such as grooves and lands are molded into the plastic motorcomponent, thereby eliminating processes such as electrochemicalmachining. Further, in an embodiment, a plastic hub is utilized to facea thrustplate, replacing a counterplate, and reducing expensive sleevemachining.

It will be apparent that features of the discussion and claims may beutilized with disc drives, low profile disc drive memory systems,spindle motors, various FDB design motors including hydrodynamic andhydrostatic motors, and other motors employing a stationary and arotatable component, including motors employing conical bearings.Further, embodiments of the present invention may be employed with afixed shaft or a rotating shaft. Also, as used herein, the terms“axially” or “axial direction” refers to a direction along a centerlineaxis length of the shaft (i.e., along axis 204 of shaft 212 shown inFIG. 2A), and “radially” or “radial direction” refers to a directionperpendicular to the centerline length of the shaft 212. Also, as usedherein, the expressions indicating orientation such as “upper”, “lower”,“top”, “bottom” and the like, are applied in a sense related to normalviewing of the figures rather than in any sense of orientation duringparticular operation, etc. These orientation labels are provided simplyto facilitate and aid understanding of the figures and should not beconstrued as limiting.

Referring to the drawings wherein identical reference numerals denotethe same elements throughout the various views, FIG. 1 illustrates a topplan view of a disc drive data storage device 110 in which the presentinvention is useful. Clearly, features of the discussion and claims arenot limited to this particular design, which is shown only for purposesof the example. Disc drive 110 includes housing base 112 that iscombined with cover 114 forming a sealed environment to protect theinternal components from contamination by elements outside the sealedenvironment. Disc drive 110 further includes disc pack 116, which ismounted for rotation on a motor (described in FIG. 2A) by disc clamp118. Disc pack 116 includes a plurality of individual discs, which aremounted for co-rotation about a central axis. Each disc surface has anassociated head 120 (read head and write head), which is mounted to discdrive 110 for communicating with the disc surface. In the example shownin FIG. 1, heads 120 are supported by flexures 122, which are in turnattached to head mounting arms 124 of actuator body 126. The actuatorshown in FIG. 1 is a rotary moving coil actuator and includes a voicecoil motor, shown generally at 128. Voice coil motor 128 rotatesactuator body 126 with its attached heads 120 about pivot shaft 130 toposition heads 120 over a desired data track along arc path 132. Thisallows heads 120 to read and write magnetically encoded information onthe surfaces of discs 116 at selected locations.

A flex assembly provides the requisite electrical connection paths forthe actuator assembly while allowing pivotal movement of the actuatorbody 126 during operation. The flex assembly (not shown) terminates at aflex bracket for communication to a printed circuit board mounted to thebottom side of disc drive 110 to which head wires are connected; thehead wires being routed along the actuator arms 124 and the flexures 122to the heads 120. The printed circuit board typically includes circuitryfor controlling the write currents applied to the heads 120 during awrite operation and a preamplifier for amplifying read signals generatedby the heads 120 during a read operation.

FIG. 2A is a sectional side view of a FDB motor that can be used in adisc drive data storage system 110, as in FIG. 1. The motor includes aninner component and an outer component, wherein the inner component andthe outer component are positioned for relative rotation, and define ajournal bearing 214 therebetween. In this example, the outer components(rotatable components) include hub 210 and hub portion 216, connected tomagnet 222. Hub 210 also includes a disc carrier member 211, whichsupports disc pack 116 (shown in FIG. 1) for rotation about shaft 212.Hub 210 is affixed to backiron 224 and magnet 222. One or more magnets222 are attached to a periphery of backiron 224. The magnets 222interact with a stator winding 220 attached to the base 202 to cause thehub 210 to rotate. Magnet 222 can be formed as a unitary, annular ringor can be formed of a plurality of individual magnets that are spacedabout the periphery of hub 210. Magnet 222 is magnetized to form one ormore magnetic poles. The inner components (stationary components)include shaft 212, which is connected to stator 220 and base 202.Additionally, this design allows for and includes shaft 212 attached totop cover 218.

Illustrated as an example, at least a portion of an outer component(i.e., hub 210 and hub portion 216) is plastic formed by a moldingprocess, wherein the hub 210 has a plastic surface that faces anddefines journal bearing 214 with the inner component (i.e., shaft 212).Alternatively, hub 210 is attached to a metal sleeve and the sleeve hasa metal surface that faces and defines journal bearing 214 with theinner component (as described in FIG. 8). In an embodiment, the plasticutilized is a liquid crystal polymer (LCP), having a carbon fiberfilling for strength reinforcement, reduction of thermal expansion, andconductivity. In an embodiment, the material utilized for the mold haslow shrinkage to ensure motor form control, and has a low moistureabsorption rate. When a conical plastic hub is employed, and the innerdiameter of the plastic hub expands, then the journal bearing gap canremain constant by the shaft repositioning lower within the journalbearing. Alternatively, when the inner diameter of the plastic hubcontracts, then the journal bearing gap can remain constant by the shaftrepositioning higher within the journal bearing.

The molding process used for forming the plastic hub is injectionmolding, although other molding processes may be alternatively employed.Further, in an embodiment, the plastic is injected using center gatingto allow for uniform radial flow across the mold cavity. Here, theplastic includes the fibrous material (i.e., carbon fiber) that isinjected into a mold center. The fibrous material thereforesubstantially aligns in a uniform direction. In an embodiment, the moldutilizes uniform heat distribution of less than 1.5 degrees Celsiussurrounding the mold cavity.

A fluid dynamic journal bearing 214 is established between the insidediameter of hub 210 and the shaft 212. A fluid, such as lubricating oilor a ferromagnetic fluid fills interfacial regions between shaft 212 andhub 210, as well as between particular other stationary and rotatablecomponents. While the present figure is described herein with alubricating fluid, those skilled in the art will appreciate that useablefluids include a lubricating liquid, lubricating gas, or a combinationof a lubricating liquid and lubricating gas. Also, typically one ofshaft 212 and hub 210 includes sections of pressure generating grooves,including asymmetric grooves and symmetric grooves. Asymmetric groovesand symmetric grooves may have a pattern including one of a herringbonepattern and a sinusoidal pattern inducing fluid flow in the interfacialregion and generating a localized region of dynamic high pressure andradial stiffness. As hub 210 rotates, pressure is built up in each ofits grooved regions and shaft 212 supports hub 210 for constantrotation. A fluid recirculation path 215 is formed through shaft 212.Fluid recirculation path 215 fluidly connects and recirculates fluidfrom journal bearing 214 to a reservoir between hub portion 216 andshaft 212, facilitating purging of air from journal bearing 214. Thefluid recirculation path 215 is shown having about a 45 degree angle,although other angles and places of connection to journal bearing 214may be employed. Alternatively, a plastic molded fluid recirculationpath is formed through plastic hub 210 to pass and recirculate fluidthrough journal bearing 214, and also to facilitate purging air fromjournal bearing 214. A fluid recirculation passageway molded by plasticis shown in FIG. 10.

Referring now to FIG. 2B, another sectional side view of a FDB motor isillustrated that can be used in a disc drive data storage system as inFIG. 1, wherein at least a portion of an outer component (i.e., hub 210)is formed of plastic by a molding process. The plastic outer componentis attached to backiron portions 224A and 224B. The backiron portions224A and 224B are inserted during the molding process of the plasticouter component. Alternatively, the backiron is bonded to the plasticouter component following the molding process. In an embodiment, thebackiron portions 224A and 224B are a ferromagnetic material such asiron or steel. The backiron is affixed to magnet 222, wherein thebackiron 224A extends axially adjacent to the magnet 222 (backironportion 224A), and also radially adjacent to a bottom portion of themagnet (backiron portion 224B). By the backiron having this form, themagnetic bias force of magnet 222 with stator 220 is thus enhanced. Thatis, counterbalancing upward and downward forces are created in the FDBmotor design. The upward force may be created by a thrustbearing betweenhub portion 216 and shaft 212. The downward force is created by themagnetic bias force of magnet 222 with stator 220. The backiron portion224B shields the magnetic forces that may occur between magnet 222 andbase 202, thereby balancing the magnetic bias force of magnet 222 withstator 220.

FIG. 3 illustrates a sectional side view of the FDB motor as in FIG. 2A,wherein draft is illustrated on the integral molded plastic outercomponent (i.e., hub 210), in accordance with an embodiment of thepresent invention. The inside diameter of the hub is set having an anglein the range of 15 degrees to 70 degrees with the axis 204 of shaft 212.In one embodiment, the inside diameter of the hub is set having an angleof 22 degrees with the axis 204 of shaft 212. The outside diameter ofthe hub 210 is set having an angle of 10 degrees with the axis 204 ofshaft 212. Other surfaces of hub 210, as shown, are set having an angleof 10 degrees with the axis 204 of shaft 212. A draft-free surface 208is intermittently situated around the outer diameter of hub 210 for thepositioning of discs. The draft-free surface 208 extends parallel to theaxis of rotation 204. The discs are thus situated at a perpendicularangle to the axis 204 of shaft 212. This draft-free surface 208 is alsoshown in FIG. 4. Additionally, in an embodiment, a parting line of themold is situated below the radial surface of disc carrier member 211.Thus, critical features of the mold are formed on the same side of themold, ensuring form control and dimensional control of the motor.

FIG. 4 is a perspective image of the FDB motor as in FIG. 2A, whereinthe plastic outer component (i.e., hub 210) defines a primary bearing215A and a secondary bearing 215B with shaft 214. Additionally, a moldeddraft free rib 208 is formed on an outer diameter of hub 210. Aspreviously described, draft-free ribs 208 are intermittently situatedaround the outer diameter of hub 210 for the positioning of discs. In anembodiment, the draft free ribs 208 are formed every 30 degrees to 45degrees about the hub 210, and are shaped small enough to avoid draggingupon mold separation.

In this motor design, the inner component shaft 214 is stationary andconical. The plastic outer component hub 210 defines a primary bearing215A and a secondary bearing 215B with the inner component shaft 214.The primary bearing 215A is formed having a less variable gap ascompared with the secondary bearing 215B. In an embodiment, the gap ofthe primary bearing 215A is about 6 microns, and the gap of thesecondary bearing 215B is in the range of 3 microns to 9 microns.Further, the primary bearing 215A maintains greater axial and radialbearing stiffness as compared with the secondary bearing 215B. Theprimary bearing 215A also substantially establishes axial positioning ofthe outer component hub 210 with respect to the inner component shaft214.

FIG. 5A illustrates a sectional side view of a FDB motor having a sleeve511 extending about a thrustplate 508 and a counterplate 506. The designof the sleeve 511 requires that the diameter 504 of the sleeve 511exceed the diameter of the thrustplate 508 and counterplate 506, suchthat the shaft 512, sleeve 511, counterplate 506, and thrustplate 508can be assembled as a single bearing unit, separate from the hub 510.The sleeve 511 is relatively expensive to machine for proper designprecision. The sleeve 511 having the form shown requires precisionmachining, especially the surfaces of sleeve 511 facing the thrustplate508 and a counterplate 506. The rotatable components in this motorexample include counterplate 506, sleeve 511, hub 510, and magnet 522,while the stationary components include shaft 512, thrustplate 508, baseplate 502, and stator 520.

FIG. 5B is a sectional side view of a FDB motor wherein the plasticouter component is a hub 550 that has a surface facing thrustplate 558,in accordance with an embodiment of the present invention. Here, theinner component is shaft 542, which is affixed to thrustplate 558. Thehub 550 is utilized to face thrustplate 558, rather than counterplate506 as shown in FIG. 5A. The hub 550 faces the radial surface and theaxial surface of the thrustplate 558. As such, the dimensions of sleeve551 are reduced, as illustrated by the diameter 554 of the sleeve 551and the axial height 555 of the sleeve 551. Machining costs are reducedsince any machining of the plastic portions of hub 550 is less expensiveas compared with machining of the sleeve 551. Further, a counterplatecan be eliminated from the motor, or used in conjunction with andaffixed to hub 550. The rotatable components in this motor exampleinclude sleeve 551, hub 550, and magnet 566, while the stationarycomponents include shaft 542, thrustplate 558, base plate 552, andstator 564.

As illustrated in FIG. 6A, a sectional side view of a FDB motor is shownwherein the plastic outer component is a hub 610 that has a surfacefacing a thrustplate 608. The thrustplate facing surface of hub 610includes grooves 614 (shown in FIG. 6B), in accordance with anembodiment of the present invention. Grooves 614 are molded in theplastic hub 610 in the shape of spirals, herringbone or other usefulform. Grooves 614 are shown in a molded spiral form in FIG. 6B. Thegrooves 614 induce fluid flow and generate a localized region of dynamichigh pressure and axial stiffness. Grooves 614 also provide an upwardforce to counterbalance a downward force created by the magnetic biasforce of magnet 622 with stator 630. The stationary components includeshaft 612 and base plate 602. Hub 610 is further illustrated with aperspective image in FIG. 6C.

Turning now to FIG. 7, a sectional side view of a FDB motor with axis704 is illustrated wherein a plastic outer component (i.e., hub 710) isaffixed to component 708. In an embodiment, component 708 is metal, andmetal component 708 faces and defines a bearing 709 with a conical innercomponent 712. In an alternative embodiment, component 708 is plasticand formed during the molding process with plastic hub 710. In yet analternative embodiment, a component 708 is formed of molded plastic andthe hub 710 is metal. In yet another alternative embodiment, the hub 710faces and defines bearing 709 with the conical inner component 712, suchthat component 708 is not utilized.

In an embodiment, the plastic hub 710 includes a fluid containmentstructure 719 formed during the plastic molding process of the hub 710.The fluid containment structure 719 and an axial top of the innercomponent 712 define a radially extending fluid reservoir 720therebetween. The rotating components in this motor include hub 710,component 708, and magnet 734. The stationary components include innercomponent 712, base plate 702 and stator 732. In an embodiment, thefacing surfaces of the hub 710 and the inner component 712 form acentrifugal fluid seal 721 therebetween.

FIG. 8 is a sectional side view of a FDB motor wherein a plastic outercomponent (i.e., hub 810) is affixed to component 808. In an embodiment,component 808 is metal, and metal component 808 faces and defines abearing 809 with a conical inner component 812. In an alternativeembodiment, component 808 is plastic and formed during the moldingprocess with plastic hub 810. In yet an alternative embodiment,component 808 is formed of molded plastic and the hub 810 is metal. Inyet another alternative embodiment, the hub 810 faces and definesbearing 809 with the conical inner component 812, such that component808 is not utilized. The rotating components in this motor include hub810, component 808 and magnet 834. The stationary components includeinner component 812, base plate 802, stator 832, and top cover 818. Theinner component 812 attaches to top cover 818.

In an embodiment, the plastic hub 810 includes a fluid fill hole 830positioned adjacent to the an axial top of the inner component 812. Thefluid fill hole 830 is formed during the molding process of plastic hub810. Alternatively, fluid fill hole 830 is formed by machining the hub810.

FIG. 9 illustrates a sectional side view of a FDB motor wherein aplastic outer component (i.e., hub 910) is affixed to component 926. Inan embodiment, component 926 is metal, and metal component 926 faces anddefines a bearing 909 with dual conical inner component 912. In analternative embodiment, component 926 is plastic and formed during themolding process with plastic hub 910. In yet an alternative embodiment,component 926 is formed of molded plastic and the hub 910 is metal. Inyet another alternative embodiment, the plastic hub 910 faces anddefines bearing 909 with the dual conical inner component 912, such thatcomponent 926 is not utilized. The rotating components in this motorinclude hub 910, component 926, and magnet 934. The stationarycomponents include dual conical inner component 912, base plate 902,stator 932, and top cover 918. The dual conical inner component 912attaches to top cover 918. Additionally, a fluid shield 914 is affixedto hub 910 to contain fluid within bearing 909 using a centrifugal fluidseal. Fluid shield 914 can be formed of plastic along with the moldingprocess of plastic hub 910. Alternatively, fluid shield 914 may bebonded to hub 910.

In an alternative embodiment, at least one of an integral plastic hub, aplastic hub affixed to a metal sleeve, or a shaft is shaped as a singlecone, a dual cone, a spherical form, or as a hemispherical form. In yetan alternative embodiment, the facing surfaces of an integral plastichub and a shaft that form a fluid bearing therebetween (or the facingsurfaces of a metal sleeve affixed to a plastic hub and the shaft thatform a fluid bearing therebetween) are shaped having a flat surface.

FIG. 10 is a sectional side view of a FDB motor wherein a plastic outercomponent (i.e., plastic hub 958) faces and defines bearings 976A and976B with inner components. The inner components include shaft 952, conesupports 954, and cones 956. Cone supports 954 are affixed to the shaft952, and cones 956 are affixed to the cone supports 954. In anembodiment of the present invention, cone supports 954 and cones 956 areformed of molded plastic along with plastic hub 958. The cone supports954 and the cones 956 define a fluid passageway 974 therebetween.Additionally, shaft 952 is attached to a top cover 964.

A fluid shield 960 is affixed to hub 958 to contain fluid withinreservoir 972 using a centrifugal fluid seal. As fluid circulatesthrough fluid passageway 974 and through bearings 976A and 976B, air isforced toward reservoir 972 and purged from the FDB motor. Further, airvents 962 are structured to provide an air passageway between the innerdiameter of cone supports 954 and the outer diameter of shaft 952. In anembodiment, air vents 962 extend the entire length of the cone support954, and allow the plenum 968 to communicate with air outside the FDBmotor.

Modifications and variations may be made to the disclosed embodimentswhile remaining within the spirit and scope of the invention. Theimplementations described above and other implementations are within thescope of the following claims.

We claim:
 1. A motor comprising: an inner component; and an outercomponent comprising a portion made of plastic, wherein said inner andouter components are positioned for relative rotation and define ajournal bearing therebetween, a rotatable component includes a hub, adisc carrier member, and said outer component or said inner component,said inner and outer components are further positioned to define a fluiddynamic bearing therebetween, said portion made of plastic faces andfurther defines said fluid dynamic bearing, and a gap of said journalbearing is less variable than a gap of said fluid dynamic bearing. 2.The motor of claim 1, wherein said inner component comprises a shaft,and wherein said outer component comprises said hub.
 3. The motor ofclaim 1, wherein said outer component comprises a rib extending from anouter diameter of said outer component, and wherein said rib is operableto position a storage disc.
 4. The motor of claim 1, wherein a surfaceof said portion comprises at least one groove.
 5. The motor of claim 1,wherein said inner component comprises a shape selected from a groupconsisting of a flat surface, a single cone, a dual cone, a sphericalform and a hemispherical form.
 6. The motor of claim 1, wherein saidplastic comprises a liquid crystal polymer comprising a carbon fiberfilling.
 7. The motor of claim 1, wherein the gap of said journalbearing is about 6 microns, and the gap of said fluid dynamic bearing isin the range of 3-9 microns.
 8. The motor of claim 1, wherein said outercomponent further comprises another portion made of metal.
 9. A motorcomprising: an inner component; and an outer component comprising afirst portion and a second portion, wherein said first portion is madeof plastic, said inner and outer components are positioned for relativerotation and define a journal bearing therebetween, a rotatablecomponent includes a hub, a disc carrier member, and said outercomponent or said inner component, said inner and outer components arefurther positioned to define a fluid dynamic bearing, said first portionmade of plastic faces and further defines said fluid dynamic bearing,and a gap of said journal bearing is less variable than a gap of saidfluid dynamic bearing.
 10. The motor of claim 9, wherein said innercomponent is a shaft, said first portion is said hub, and said secondportion is a sleeve.
 11. The motor of claim 9, wherein said outercomponent comprises a rib extending from an outer diameter of said outercomponent, and said rib is operable to position a storage disc.
 12. Themotor of claim 9, wherein said inner and outer components are furtherpositioned to form a fluid reservoir.
 13. The motor of claim 9, whereinsaid inner component comprises a shape selected from a group consistingof a flat surface, a single cone, a dual cone, a spherical form and ahemispherical form.
 14. The motor of claim 9, wherein said plastic is aliquid crystal polymer comprising a carbon fiber filling.
 15. The motorof claim 9, wherein the gap of said journal bearing is about 6 microns,and the gap of said fluid dynamic bearing is in the range of 3-9microns.
 16. The motor of claim 9, wherein said second portion of saidouter component is made of metal.
 17. An apparatus comprising: a shaft;and an outer component comprising a portion made of plastic, whereinsaid shaft and outer component are positioned for relative rotation anddefine a journal bearing therebetween, a rotatable component includes ahub, a disc carrier member, and said outer component or said shaft, saidshaft and outer component are further positioned to define a fluiddynamic bearing therebetween, said portion made of plastic faces andfurther defines said fluid dynamic bearing, and a gap of said journalbearing is less variable than a gap of said fluid dynamic bearing. 18.The apparatus of claim 17, wherein a surface of said portion comprisesat least one groove.
 19. The apparatus of claim 17, wherein said shaftcomprises a shape selected from a group consisting of a flat surface, asingle cone, a dual cone, a spherical form and a hemispherical form. 20.The apparatus of claim 17, wherein said outer component furthercomprises another portion made of metal.